This symposium will include a series of presentations covering recent advances in Drosophila molecular and developmental genetics and will provide a review of the contributions of Drosophila research to the investigations of the major problems in the study of eukaryotic developmental biology. Using the unique methodology made possible by the use of Drosophila as an experimental tool, the speakers will present concepts and results which clarify and help explain problems of determination, stabilization and differentiation in higher organisms. The presentations will emphasize research on the genetic control of development at the cellular biochemical and molecular level (e.g. the control of genetic transcription and translation) as well as at the tissue and organ level (e.g. the control of cell to cell and tissue to tissue interactions). The sessions will be organized around the contributions of Drosophila research to problems in gametogenesis, in determination and stabilization of imaginal development, in the polygenic control of developmental interactions, in the hormonal control of development and differentiation, and in the regulation of gene activity at the molecular and morphological levels. The symposium will be published as the first comprehensive review in over ten years of the contributions of Drosophila genetics to problems in cellular and developmental biology.